override package dependencies with requirements file when requested

[zacharyburnett]

Resolves SCSB-66

Currently, tox installs the requirements-dev.txt before installing the package with pip install .; this could result in the possible edge case where package dependencies override the requirements file, where the opposite should be the case, as seen in spacetelescope/jwst#7557

Checklist

• [N/A] added entry in CHANGES.rst under the corresponding subsection
• updated relevant tests
• [N/A] updated relevant documentation
• [N/A] updated relevant milestone(s)
• added relevant label(s)

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (21c1358) 64.51% compared to head (6b235e3) 64.51%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #685   +/-   ##
=======================================
  Coverage   64.51%   64.51%           
=======================================
  Files          78       78           
  Lines        4106     4106           
=======================================
  Hits         2649     2649           
  Misses       1457     1457           

Flag	Coverage Δ		*Carryforward flag
nightly	63.59% <ø> (ø)		Carriedforward from 21c1358

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[zacharyburnett]

docs have the deprecation warning from asdf-format/sphinx-asdf#58

[ddavis-stsci]

LGTM